Chennai, Mar 12 (IANS): The Tamil Nadu Police has sent the mobile phones confiscated from the four persons arrested in connection with the Pollachi sexual assault case, for analysis in an effort to gather more details, a police official told IANS here on Tuesday.

The Coimbatore (Rural) Police believes that the network of criminals will be about 15 members and are currently probing it.

Pollachi, a town in Coimbatore district, is about 535 km from here.

The four accused -- Thirunavukkarasu, Sabarirajan, Vasanthakumar, Satish -- were arrested in connection with the crime.

According to the police, the accused would befriend women on social media first. After gaining the girl's confidence, she would be invited to a secluded place and sexually assaulted which was also videographed.

Later the victims were blackmailed for money or for physical submission.

With opposition parties claiming that the ruling AIADMK was trying to shield its members alleged to have been involved in the crime, the party on Monday expelled worker A. Nagaraj for assaulting a victim's brother.

Meanwhile, V. Jayaraman, deputy speaker of the Tamil Nadu Assembly, told the media that opposition parties were trying to spread rumours to tarnish his name by linking his family members to the alleged crime.

Thirunavukkarasu, when he was in hiding, released a video saying politicians were also involved and wanted the case to be transferred to the Central Bureau of Investigation (CBI).